DESCRIPTION: Almost the entire fellowship will involve research which will concentrate on the effect of thyroid hormone on the rat submandibular gland. Dr. Dodds will investigate, first of all, the short-term effects of thyroid hormones (T3) on isolated submandibular acinar cells. The effect of T3 will be studied in adult male rats and neonatal rats. More specifically, the effect of T3 on cyclic AMP accumulation, on intracellular calcium concentrations, and on calcium fluxes across cell membranes will be investigated. Calcium intake and efflux will be investigated as separate phenomena. Dr. Dodds will also investigate experimentally-induced hypo- and hyperthyroidism in adult rats. Changes in thyroid status will be investigated as to their effects on the b adrenergic receptor function and on gene expression. The effect of hypo- and hyperthyroidism will also be investigated on submandibular development in neonatal rats. The expression of c-fos, the b adrenergic receptor and cystatin S mRNA will be determined. The effect of T3 on a rat submandibular cell line will also be tested. These cells will be analyzed as to their response to T3 and then tested as to whether or not T3 has an effect on function or on the level of expression of receptors and the other proteins. In addition, the effect on cell proliferation and the signaling involved will be tested as a function of T3. The other activities that are part of Dr. Dodds' training plan include attending a Cell Biology course at the Graduate School of Biomedical Sciences at the UTHSCSC. This would constitute a 4% time commitment over the first year of the award. Additional activities would include active interaction with scientists in the sponsor's laboratory, participation in a number of regularly scheduled meetings (laboratory and departmental), and participation in short courses and workshops on molecular biology techniques and on grant application preparation.